The present technique relates to an apparatus and method for detecting a resonant frequency giving rise to an impedance peak in a power delivery network.
When designing power delivery networks used to distribute a supply voltage to components of a data processing system, one or more resonant frequencies can occur within the power delivery network that can give rise to corresponding impedance peaks. When such an impedance peak occurs, this can give rise to a corresponding drop in the supply voltage provided to the components, and hence it is important to know the frequencies at which such impedance peaks occur, so as to allow the system incorporating the power delivery network and the various components operating from the supply voltage to be configured to operate taking into account the presence of those impedance peaks.
When designing the power delivery network it is possible to determine where the impedance peaks should appear. However, when the systems incorporating the power delivery network design are manufactured, it has been found that the resonant frequencies, and hence the impedance peaks, may differ from the values calculated at design time, and accordingly it is desirable to seek to measure the resonant frequencies in the manufactured system. In particular, if the resonant frequencies differ from the values calculated at design time, this can cause significant performance issues, which can result in certain faults arising during operation of the data processing system, for example due to timing errors.
However, known techniques for seeking to determine the locations of the impedance peaks within the frequency spectrum suffer from a number of disadvantages. For example, AC supply impedance may be measured using a time-domain approach of measuring a step or impulse response and converting this into a frequency-domain impedance plot. However, this typically requires dedicated voltage sense pins and off-chip measurement circuits such as oscilloscopes, which adds significant cost to the manufacturing test process.